The present invention relates to a packet broadcasting method, and more particularly, to a packet broadcasting method for group broadcasting a data packet transmitted by a broadcasting source terminal to a plurality of broadcast destination terminals.
A technique for broadcast communication or the broadcasting operation in a packet switching system, is described in JP-A-61-140251 is known.
In the prior art, a broadcasting table in which called terminals or destination terminals are defined for each calling terminal or source terminal is provided in a packet switching office, and the packet switching office performs the broadcasting operation on the basis of the broadcasting contents of the table.
In the prior art, since the broadcasting or the broadcast communication is performed in the packet switching office including the broadcasting function, it is necessary to add the broadcasting function in an existing packet switching network when the existing packet switching network is to realize the broadcasting. Accordingly, there is a problem that it is difficult to attain the broadcasting operation in the existing packet switching network. Further, there is a problem that a large amount of pre-defined data is required since destination terminals are required to be pre-defined for each source terminal effecting the broadcasting operation.
Furthermore, in the prior art, when a broadcast destination terminal is added or changed, it is necessary to change the pre-defined data stored in the packet switching office and accordingly flexibility is lacking in such a system. The broadcasting table is pre-defined for each source terminal effecting the broadcasting operation, while since the table has no table identification, only one group of destination terminals is pre-defined for each source terminal. Accordingly, there is a problem that it is impossible to select broadcast destination terminals depending on the contents of data to be broadcast.
In addition, in the prior art, when a data packet is transmitted to destination terminals, a packet switching office which has received the data packet from a source terminal directly transmits the data packet to all of the destination terminals individually. Accordingly, when the destination terminals are increased, there is a problem that a time required to perform the whole broadcasting operation in the packet switching office is lengthened to thereby enlarge differences in reception times of the data packet among the destination terminals and increase trunk traffic in the packet switching network which adversely affects other communication.